Photons v. Protons: Show Us The Data!

Our guest blogger is Emily Oshima, a research associate/policy analyst with the Health Policy team at American Progress.

Earlier this week, CAP Senior Fellow and oncologist Zeke Emanuel co-authored an editorial that questions the increasing use of proton beam therapy to treat cancer patients, given the clear lack of clinical evidence on its efficacy and substantially higher costs.

In theory, proton beam therapy can zap cancerous tissue with much greater precision than conventional photon radiation treatment, minimizing damage to healthy tissue surrounding a malignancy and reducing side effects. Although proton beam therapy has been in use since the 1950s, randomized clinical trials for the treatment of prostate cancer -– which proton therapy is frequently used to treat — are completely lacking. Existing studies are smaller, single institution, and short-term, and are unable to evaluate long-term outcomes, including onset of delayed side-effects. Additionally, although proton beam therapy has been shown to effectively treat certain rare childhood cancers — mainly brain and spinal cord tumors — the treatment’s precision may actually miss potentially treatable disease that could be addressed through less-precise x-rays.

As major medical centers — including the University of Pennsylvania, M.D. Anderson, and the Mayo Clinic, among others –- invest hundreds of millions of dollars in building the football-field-size buildings needed to house the proton accelerators and in light of rapidly rising health care expenditures, we’re forced to ask, “It Costs More, but Is It Worth More?”


It seems that Mayo Clinic President and C.E.O. John Noseworthy might have an answer in several years, after spending more than $360 million building two new Mayo proton beam facilities, inevitably passing at least some of these costs on to cancer patients. Noseworthy states that Mayo, along with other proton centers in the U.S., will enroll patients in clinical trials once their proton facilities are up and running. But even if the results of the planned phase III clinical trials show that the protons are no more effective than photons, Mayo and others would still continue to use the machines, given their substantial up-front investment in the technology.

In his editorial, Noseworthy also claims that “hundreds of manuscripts” were reviewed over a six-year period to research the effectiveness of the treatment. Yet, he does not cite a single study, and doesn’t refute the lack of randomized clinical trials, the gold standard of clinical effectiveness assessments. If proton beam therapy does, in fact, produce more effective treatment outcomes, improve quality of life for cancer patients through reduced side effects and minimal damage to surrounding tissue, it may be a worthy investment for a wider population of cancer patients. But until then — show us the data!